1. Field of the Invention
This invention pertains to infrared detection systems. In particular, this invention directs itself to the detection and determination of the compositional states of a chemical compound by measuring the absorption of radiation having a bandwidth within the infrared portion of the electromagnetic spectrum. More in particular, this invention relates to the detection of the presence on a surface of differing phases of a compound, and simultaneously measuring the thickness of each of the phases by comparing the energy absorption at two discrete wavelengths within the infrared portion of the electromagnetic energy spectrum.
Additionally, this invention relates to the detection of ice, frost and/or moisture layers formed on a surface, and the measurement of the thickness of those layers, after detection and measurement of the magnitude of radiation absorbed at each of two discrete wavelengths of infrared radiation. Still further, the subject invention relates to the simultaneous application of two discrete wavelengths of infrared radiation to (1) a reference detector, and, (2) a test detector having a surface upon which there is a formation of ice and/or moisture. Still further, this invention relates to the measurement of the thickness of layers of ice, frost and/or moisture formed on a test surface by comparison of the energy absorbed at two discrete wavelengths of infrared radiation with the absorption characteristics of ice and water at those discrete wavelengths of infrared radiation.
2. Prior Art
Infrared detection systems and detection systems for ice in particular are known in the art. Additionally, infrared detection systems capable of differentiation between ice and water are known in the art. However, while prior art detection systems may use two wavelengths of infrared radiation, they apply one wavelength as a reference signal and the other as a test or measurement signal. Generally, such prior art systems select a wavelength of infrared radiation for the test or measurement signal such that absorption by ice is maximized.
Thus, such prior art systems while being capable of differentiating between ice or water formed on a surface, they could only provide a measurement of ice thickness. In opposition, the subject ice detection and measurement system applies two discrete wavelengths of infrared radiation at the same time to both a reference detector and a test detector. Both wavelengths used by the subject system are applied as detection signals and reference signals, such that the differences between the absorption of infrared radiation by any ice and/or water formed on the test surface at each of the two discrete wavelengths is determined. The subject system is therefore not limited to just determining the presence of ice or water, or the measurement of either one, but provides the detection of both ice and water, a measurement of the thickness of accumulations of both the ice and the water, and therefore, monitors the progress of any icing/de-icing process.
The best prior art known to Applicant includes U.S. Pat. Nos. 2,359,787; 4,054,255; 4,274,091; 4,593,533; 4,578,959; 3,471,698; 3,732,016; 3,735,136; 3,540,025; 2,476,217; 2,446,885; 3,188,828; 3,280,577; and, 3,946,286.